public class Offer69 {
    public int peakIndexInMountainArray(int[] arr) {
        int left = 0, right = arr.length - 1;
        while(left <= right){
            int mid = left + (right - left) / 2;
            if(arr[mid] > arr[mid + 1]){
                right = mid - 1;
            }
            else {
                left = mid + 1;
            }
        }
        return left;
    }

    public static void main(String[] args) {
        Offer69 o = new Offer69();
        System.out.println(o.peakIndexInMountainArray(new int[]{0,1,0}));
    }
}
